1. Field of the Invention
The present invention relates to a solar cell module with excellent long-term reliability and a solar cell integrated cladding assembly with excellent long-term reliability in which a solar cell module is mounted on a base member.
2. Related Background Art
As people's awareness is increasing about ecology in recent years, solar cells become more and more expected as a clean energy source. Particularly, examples of installation on tiled roofs of houses and on roofs and walls of buildings are also increasing year after year.
In addition to the solar cells installed on the roofs of houses, development and construction is also extensively being made in modules integrated with the roof or the wall, such as building material/roof integrated solar cell modules or building material/wall integrated solar cell modules.
For example, Japanese Patent Application Laid-Open No. 7-211932 describes a solar cell module integrated roof material of the batten seam type to be mounted through spacer members on a base member of wood, mortar, cement, or the like. In this example, the adjacent solar cell modules of the batten seam type are electrically connected to each other by connector integrated cords in the space between the solar cell modules and the base member.
In Japanese Patent Application Laid-Open No. 7-302924 discloses a plurality of horizontally roofing type solar cell integrated roof plates are mounted on the roof member, wherein wires for electrically connecting adjacent solar cell integrated roof plates are set through the space between the roof member and the horizontally roofing type solar cell integrated roof plates. In the case of such solar cell integrated roof plates, the wires for electrically connecting the adjacent solar cell integrated roof plates, i.e., connectors and connection cables, are connected in the space between the base member, such as a sheathing roof board, and the solar cell integrated roof plates.
As described above, in the case where the solar cell modules are mounted on the base member and the adjacent solar cell modules are connected by connection wires such as cables and connectors, it is common practice to employ a method of successively mounting the solar cell modules on the base member while wiring the connection wires of the adjacent solar cell modules in the space between the base member and the solar cell modules.
Specifically, for example, after an eaves-side solar cell module is fixed on a frame or the like, connection wires of the eaves-side solar cell module and a ridge-side solar cell module immediately above it are electrically connected, for example, through connectors or the like in the space between the base member and the solar cell modules, and then the ridge-side solar cell module is also fixed to the frame.
However, in this installation method, it was difficult to conduct the work of electrical connection, because the space was narrow between the base member and the solar cell modules and because the connecting work was not allowed to be carried out on the front surface side but had to be carried out on the back surface side of the modules. Further, the work became harder at low temperatures in winter, because the cables and connectors became hard.
Further, since the connecting work of connection wires had to be carried out in the narrow space, the connection wires were sometimes pulled by force and excessive force was sometimes exerted on the connection wires and the connecting parts between the solar cell modules and the connection wires. There were some cases where the connection wire was detached from the solar cell module.
Thus, it is conceivable to increase the length of the connection wires of the solar cell modules so as to facilitate the connecting work of the connection wires between the solar cell modules in terms of operability and reliability. However, the increase of the length of the connection wires of the solar cell modules inevitably makes the connection wires such as output leads of the solar cell modules more likely to be in contact with the base member.
In general, plastics such as polyvinyl chloride and polyethylene resins are popularly used in the field of wire covering. Among such plastics, polyvinyl chloride resin demonstrates flexibility, which is hardly achieved by the other plastics, when blended with a plasticizer, and it has well-balanced electrical, physical, and chemical properties and high workability and coloring characteristics as well. Further, polyvinyl chloride resin is relatively inexpensive and thus is also used for the cables of the solar cell modules. A typical plasticizer for polyvinyl chloride is di(2-ethylhexyl) phthalate (DOP; dioctyl phthalate), which is widely used in terms of well-balanced performance and price.
The inventors, however, found that in the case of a solar cell integrated cladding assembly in which the solar cell modules were mounted on the base member and were electrically connected in the space between the base member and the solar cell modules, there arose no problem where the connection wires of the solar cell modules were not in contact with the base member but there arose the following problem where the connection wires of the solar cell modules were physically in contact with the base member.
Specifically, the inventors have found that where the electrical connection wires of polyvinyl chloride type resin containing a phthalic acid ester type plasticizer were kept in contact over a long period with the base member of asphalt type resin, polyvinyl chloride type resin, polystyrene type resin, polyurethane type resin, or the like used mainly for waterproofing and where they were placed under severe conditions, the electrical connection wires were deteriorated to degrade the performance of the solar cell modules.